(1) Field of the Invention
The present invention is directed to compact antennas. In particular, the present invention is directed to a compact antenna that has the ability to operate on or near electrically conducting surfaces.
(2) Description of the Prior Art
The shielding effectiveness (SE) of a metallic enclosure is an important figure of merit that describes the degree of protection against electromagnetic field leakage into or out of the structure. It is defined by a ratio in dB units by equation (1) as follows:
                    SE        =                  20          ⁢          log          ⁢                                                                E                t                                            E                i                                                                                    (        1        )            Where Ei is the electric field strength leaking into the shield, and Ei is the incident field strength external to the shield. Both field strengths have units of volts per meter (V/m). The degree of protection against electromagnetic field leakage is particularly relevant to compact antennas whose design are in the nature of portable metallic enclosures and whose application requires the ability to operate on or near electrically conducting surfaces.